Japanese patent application publication No. 2002-308224 discloses a method and an apparatus for supplying bags each of which is filled with a solid material and has an unsealed bag opening, to a packaging machine for carrying out other packaging processes (such as filling of a liquid material, a decompression processing, and sealing of the bag opening) one after another.
According to these supplying method and apparatus, a bag which is filled with a solid material and which has an unsealed bag opening is placed on a belt conveyor; the bag with a horizontal posture is intermittently conveyed while the bag opening faces forward; the bag is stopped at a stop position (a takeoff position) provided on the conveyance path; the both side edges of the bag near the bag opening are held by a pair of holding members after positioning of the bag is carried out at the stop position by causing guide members (a pair of guide members) to contact the both side edges of the bag from the both sides; and then the posture of the bag is changed from the horizontal posture to a vertical posture while the bag is moved along a predetermined transfer pathway to a delivery position. The bag of which the posture has been changed to the vertical posture is delivered to a pair of grippers of the packaging machine via a bag delivery device.
The pair of guide members has a function in which the pair of guide members contacts the both side edges of a bag from the both sides, and if the bag deviates from a proper position (being a position at which the bag is to be situated), the pair of guide members moves the bag in the width direction, in such a manner that the center of the width of the bag corresponds to the center of the pair of holding members (that is, the bag is positioned). With this, symmetric parts of the both side edges of the bag are evenly held by the pair of holding members, and when this bag is delivered to a pair of grippers of the packaging machine by means of the bag delivery device, the center of the width of the bag can correspond to the center of the pair of grippers.